Compilare: user.c:7:34: warning: built-in function ‘pow’ declared as non-function int long nr, Numbers[100005], i, pow; ^~~ user.c: In function ‘main’: user.c:27:8: warning: implicit declaration of function ‘strlen’ [-Wimplicit-function-declaration] vf=strlen(Expression); ^~~~~~ user.c:27:8: warning: incompatible implicit declaration of built-in function ‘strlen’ user.c:27:8: note: include ‘<string.h>’ or provide a declaration of ‘strlen’ user.c:26:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%s", Expression); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~